Deck 4: Thermodynamics Laws, Processes, and Efficiency

Question 1

For storing a gas which one of the following types of compression will be ideal

A)constant volume
B)polytropic
C)adiabatic
D)isothermal

Answer 1

isothermal

Question 2

A process which can be stopped at any stage & reversed so that the system & the surroundings are exactly restored to their initial states is known as

A)thermodynamic process
B)irreversible process
C)reversible process
D)isothermal process

Answer 2

reversible process

Question 3

Which of the following is a reversible process?

A)throttling
B)combustion
C)free expansion
D)extension &compression of a spring

Answer 3

extension &compression of a spring

Question 4

Leaking of air from a punctured tube is an example of

A)isothermal expansion
B)adiabatic expansion
C)throttling
D)constant pressureexpansion

Question 5

To convert volumetric analysis to gravimetric analysis, the relative volume of each constituent of the flue gases is

A)divided by its specific weight
B)multiplied by its density
C)multiplied by its molecular weight
D)divided by its molecular weight

Question 6

a heat engine receives heat at the rate of 1500 kJ/min.& gives an output of 8.2 kW. Its thermal efficiency is equal to

A)20.5 %
B)30.2%
C)32.8%
D)44.6%

Question 7

Consider the following statements: The definition of
1) temperature is due to zeroth law of thermodynamics
2) entropy is due to first law of thermodynamics
3) internal energy is due to second law of thermodynamics
4) reversibility is due to Kelvin-Planck's ststement of these statements

A)1,2 & 3 are correct
B)1,3 & 4 are correct
C)1 alone is correct
D)2 alone is correct

Question 8

A heat engine is supplied with 250 kJ/s of heat at a constant fixed temperature of 227°C. The heat is rejected at 27°C. The cycle is reversible, if the amount of heat rejected is

A)273 kj/s
B)200 kj/s
C)180 kj/s
D)150 kj/s

Question 9

A Carnot engine receiving heat at 400K has an efficiency of 25%. The C.O.P. of a Carnot refrigerator working between the same temperature limits is

A)1
B)2
C)3
D)4

Question 10

If a heat enine gives an output of 3 kW when the input is 10,000 J/s, then the thermal efficiency of the engine will be

A)20%
B)30%
C)70%
D)76.7%

Question 11

The fundamental unit of enthalpy is

A)mlt ^-2
B)ml²t^-1
C)ml²t ^-2
D)ml³t ^-2

Question 12

In a cyclic heat engine operating between a source temperature of 600°C & a sink temperature of 20°C, the least rate of heat rejection per kW net output of the engine is

A)0.460 kw
B)0.505 kw
C)0.588 kw
D)0.650 kw

Question 13

In a reversible cycle, the source temperature is 227°C & the sink temperature is 27°C. The maximum available work for a heat input of 100 kJ will be

A)100 kj
B)60 kj
C)40 kj
D)88 kj

Question 14

A heat engine using lake water at 12° C as source & the surrounding atmosphere at 2°C as sink executes 1080 cycles per min. If the amount of heat drawn per cycle is 57J, then the output of the engine will be

A)66 w
B)56 w
C)46 w
D)36 w

Question 15

One reversible heat engine operates between 1600 K & T? K & another reversible heat engine operates between T? K & 400 K. If both the engines have the temperature T? must be equal to

A)100 kj
B)1200 k
C)1400 k
D)800 k

Question 16

An engine receives 15152 J/s of heat & produces 5 KW of power. The efficiency of the engine is

A)25%
B)27.5%
C)30%
D)33%

Question 17

Choose the correct statement

A)pressure, temp. & entropy are extensiveproperties
B)pressure, temp. & entropy are intensiveproperties
C)pressure, volume & temp. are extensive properties
D)volume & entropy are extensive properties

Question 18

Which law of thermodynamics defines entropy

A)first
B)second
C)third
D)zeroeth

Question 19

Which of the following processes is essentially irreversible

A)isothermal
B)adiabatic
C)isentropic
D)thrittling

Question 20

A thermodynamic cycle operates between 400 K. & 290 K. 500 MJ/s of heat is added to the working substance. The power generated is

A)290 mw
B)290 mj
C)137.5 mw
D)137.5 mj

Question 21

A reversible engine performing as engine has efficiency of 62.5%. If it is reversed to work as refrigerator its COP will be

A)60%
B)62.5%
C)65%
D)37.5%

Question 22

A reversible engine performing as refrigerator has COP=33%. If the same machine operates as engine, its efficiency will be

A)67%
B)33%
C)75%
D)37.5%